finding 27.1 : natural-processes-rate-to-reduce-co2-concentration

Carbon dioxide is removed from the atmosphere by natural processes at a rate that is roughly half of the current rate of emissions from human activities. Therefore, mitigation efforts that only stabilize global emissions will not reduce atmospheric concentrations of carbon dioxide, but will only limit their rate of increase. The same is true for other long-lived greenhouse gases.

New information and remaining uncertainties: There are several important uncertainties in the current carbon cycle, especially the overall size, location, and dynamics of the land-use sink4f2b13fe-2d6e-496f-a58e-8fd54225bd862e074f83-cc54-4c67-afdf-04484f5c464a and technological development and performance.
Simulating future atmospheric concentrations of greenhouse gases requires both assumptions about economic activity, stringency of any greenhouse gas emissions control, and availability of technologies, as well as a number of assumptions about how the changing climate system affects both natural and anthropogenic sources.

Assessment of confidence based on evidence: Very High. Observations of changes in the concentrations of greenhouse gases are consistent with our understanding of the broad relationships between emissions and concentrations.